Biology unit 20

Question 1

Food production part 1

Answer 1

Agricultural machinery has replaced humans and improved efficiency due to the ability to farm much larger areas of land

Chemical fertilisers improve yields - fertilisers increase the amount of nutrients in the soil for plants, meaning that they can grow larger and produce more fruit.

Question 2

Food production part 2

Answer 2

Insecticides and herbicides - these chemicals kill off unwanted insects and weed species, meaning that there is less damage done to plants and fruit lost to insects, as well as reducing competition from other plant species (herbicides)

Question 3

food production part 3

Answer 3

Selective breeding - animals and crop plants which produce a large yield are selectively bred to produce breeds that reliably produce high yields

Question 4

Advantages of large scale monocultures of crop plants

Answer 4

It makes farming much more efficient, keeping costs down. Machines and procedures can be used totally systematically on a large scale.

Question 5

Disadvantage of large scale monocultures of crop plants

Answer 5

increased vulnerability to pests and diseases. When a single crop is grown over a large area, it creates an ideal environment for pests and pathogens that can devastate the entire crop.

Question 6

Advantages of intensive livestock production

Answer 6

The cost of production is lower
therefore food can be sold at cheaper prices

There is a lower requirement for labour to produce the food

Question 7

Disadvantage of intestive livestock production

Answer 7

Ecological issues with the reduction in biodiversity in areas where large amounts of land are used to graze cattle

Intensive farming techniques tend to use
- pesticides which can cause negative effects on the foodchain

Question 8

Describe biodiversity

Answer 8

as the number of different species that live in an area

Question 9

Reasons for habitat destruction

Answer 9

• marine pollution - eutrophication can occur when fertilisers from intensively farmed fields enter waterways, causing high decrease in biodiversity as most aquatic species living there die from lack of oxygen

Question 10

Reasons of habitat destruction part 3

Answer 10

• extract of natural resources- many trees are cut down to create products destroying forest habitats. In addition some resource extraction takes up a large amount of space

Question 11

Reasons of habitat destruction - Clearing land for farming and housing

Answer 11

Crops, livestock and homes take up a large amount of space

As there is an increase in population in demand for food, the amount of land available for these things must be increased by clearing habitat e.g forest

Question 12

Describe a sustainable resource

Answer 12

as one which is produced as rapidly as it is removed from the environment so that it does not run out

Question 13

Why organisms become endangered or extinct part 2

Answer 13

This not only reduces their numbers but can also disrupt ecological balance, affecting other species that rely on them for food or other ecological functions. Pollution introduces harmful substances into ecosystems, affecting air, water, and soil quality, which can lead to health problems in wildlife and a decline in species populations. This invasive nature can lead to a decline in biodiversity, as native species struggle to survive in the face of these new competitors .

Question 14

Process of eutrophication of water

Answer 14

Runoff of fertiliser from farmland enters the water and causes increased growth of algae and water plants
The resulting ‘algal bloom’ blocks sunlight so water plants on the bottom start to die, as does the algae when competition for nutrients becomes too intense
As water plants and algae die in greater numbers, decomposing bacteria increase in number and use up the dissolved oxygen whilst respiring aerobically
As a result there is less oxygen dissolved in water, so aquatic organisms such as fish and insects may be unable to breathe and would die

Question 15

Explain how tree be conserved

Answer 15

replanting similar/same trees when mature trees are cut, ensuring that there will be adequate supply in the future

Education helps to ensure logging companies are aware of sustainable practices and consumers are aware of the importance of buying products made from sustainable sources

Question 16

Explain how fish stocks can be conserved

Answer 16

Controlling the time of year that certain fish can be caught (to prevent large scale depletion of stocks when fish come together in large numbers in certain areas to breed)
Restocking (breeding and keeping offspring until they are large enough to survive in their natural habitat then releasing)
Educating everyone so they are aware of types of fish which are not produced sustainably and can avoid them when buying fish

Question 17

Effects of non biodegradable plastics - aquatic

Answer 17

Animals often try to eat plastic or become caught in it, leading to injuries and death. As the plastic breaks down it can release toxins that affect marine organisms. Once it has broken down into very small particles, it is commonly ingested by animals and enters the food chain

Question 18

Effects of non bioplastics - ecosystem

Answer 18

Plastic is generally disposed of by burying in landfills. As it breaks down, it releases toxins into the surrounding soil and as such the land is no good for growing crops or grazing animals and can only be used for building on several decades after burial

Question 19

Flooding and extinction/loss of biodiversity

Answer 19

• flooding - without trees the topsoil will be loose and unstable so will be easily washed away by rain, increasing the risk of flash flooding/landslides
• extinction - forest habitats have a huge range of biodiversity, but as it’s getting destroyed at a fast rate, it causes the loss of numbers of plant/animal species that are only found in these areas and therefore will become extinct.

Question 20

Soil erosion

Answer 20

• trees will usually take up nutrients and minerals from the soil through their roots. The loss of soil nutrients is permanent and makes it very difficult for forest trees to regrow, even if the land is not cultivated with crop plants or grass.

Question 21

Increased co2 in atmosphere

Answer 21

• when areas of land in forests are cleared for land use, the trees often as opposed to being cut down, this further increases the co2 levels in the atmosphere, contributing to global warming.

Question 22

Resources conserved

Answer 22

some resources can be conserved and managed sustainably, limited to forests and fish stocks

Question 23

How endangered species can be conserved

Answer 23

education programmes

captive breeding programmes

monitoring and legal protection of the species and of their habitats

seed banks as a conservation measure for plants - seeds of endangered plant species are carefully stored so that new plants may be grown in the future

Question 24

reasons for conservation programmes part 1

Answer 24

• Maintaining or increasing biodiversity
  Which allows ecosystems to remain stable
• Reducing extinction - Helps to retain iconic species and maintain biodiversity
• Protecting vulnerable ecosystems which would have been quickly lost to human activity.

Question 25

Reasons for conservation programmes part 2

Answer 25

• Maintaining ecosystem functions
  Nutrient cycling eg. carbon cycling to hold back climate change
  Resource provision, such as
  Food - making sure we have enough for the population
  Drugs - having access to plants for plant-based remedies
  Fuel - for improtant activities such as cooking
  Genes - so the gene pool remains wide and variety exists in all species

Question 26

The risk to a species if it’s population size decreases

Answer 26

If its population size decreases, a species will experience reduced genetic variation
This renders the species more susceptible to environmental change
The species is less resilient and has a greater risk of extinction

Question 27

IVF and AI in captive breeding programmes

Answer 27

Artificial insemination (AI), allows large numbers of offspring to be produced without the need for conventional sexual intercourse between males and females

In vitro fertilisation (IVF)
This allows gametes with known alleles to be used in ensuring the next generation remains biodiverse